Vehicle transmission systems, cooling systems, and braking systems may employ clutches or like devices to selectively transmit rotational forces from a drive source to an output member. For example, some cooling systems employ fan clutches that control the output rotation of engine cooling fans. Such a fan clutch can be driven by a drive pulley that rotates in response to the vehicle engine.
In general, the clutch can be operated to engage (or disengage) opposing clutch surfaces, which rotationally interconnect (or rotationally disconnect) the drive pulley and the output member. In an example related to fan clutches, when the clutch surfaces shifted to the engaged position, the output member (carrying fan blades) is driven to rotate along with the drive pulley. However, when the clutch surfaces are shifted to the disengaged position, the output member is no longer directly urged by the drive pulley and may be free to stop rotating.